Uncoupling protein 2 deficiency of non-cancerous tissues inhibits the progression of pancreatic cancer in mice

Background: Pancreatic ductal adenocarcinoma(PDAC) is a disease of the elderly mostly because its development from preneoplastic lesions depends on the accumulation of gene mutations and epigenetic alterations over time. How aging of non-cancerous tissues of the host affects tumor progression, however, remains largely unknown. Methods: We took advantage of a model of accelerated aging, uncoupling protein 2-deficient( Ucp2 knockout, Ucp2 KO) mice, to investigate the growth of orthotopically transplanted Ucp2 wild-type(WT) PDAC cells(cell lines Panc02 and 6606PDA) in vivo and to study strain-dependent differences of the PDAC microenvironment. Results: Measurements of tumor weights and quantification of proliferating cells indicated a significant growth advantage of Panc02 and 6606PDA cells in WT mice compared to Ucp2 KO mice. In tumors in the knockout strain, higher levels of interferon-γ m RNA despite similar numbers of tumor-infiltrating T cells were observed. 6606PDA cells triggered a stronger stromal reaction in Ucp2 KO mice than in WT animals. Accordingly, pancreatic stellate cells from Ucp2 KO mice proliferated at a higher rate than cells of the WT strain when they were incubated with conditioned media from PDAC cells. Conclusions: Ucp2 modulates PDAC microenvironment in a way that favors tumor progression and implicates an altered stromal response as one of the underlying mechanisms.

Antifibrogenic effects of vitamin D derivatives on mouse pancreatic stellate cells

AIM To study the molecular effects of three different D-vitamins, vitamin D2, vitamin D3 and calcipotriol, in pancreatic stellate cells(PSCs).METHODS Quiescent PSCs were isolated from mouse pancreas and activated in vitro by seeding on plastic surfaces. The cells were exposed to D-vitamins as primary cultures(early-activated PSCs) and upon re-culturing(fullyactivated cells). Exhibition of vitamin A-containing lipid droplets was visualized by oil-red staining. Expression of α-smooth muscle actin(α-SMA), a marker of PSC activation, was monitored by immunofluorescence and immunoblot analysis. The rate of DNA synthesis was quantified by 5-bromo-2'-deoxyuridine(Brd U) incorporation assays. Real-time PCR was employed to monitor gene expression, and protein levels of interleukin-6(IL-6) were measured by ELISA. Uptake of proline was determined using 18 F-proline.RESULTS Sustained culture of originally quiescent PSCs inducedcell proliferation, loss of lipid droplets and exhibition of stress fibers, indicating cell activation. When added to PSCs in primary culture, all three D-vitamins diminished expression of α-SMA(to 32%-39% of the level of control cells; P < 0.05) and increased the storage of lipids(scores from 1.97-2.15 on a scale from 0-3; controls: 1.49; P < 0.05). No such effects were observed when D-vitamins were added to fully-activated cells, while incorporation of Brd U remained unaffected under both experimental conditions. Treatment of re-cultured PSCs with D-vitamins was associated with lower expression of IL-6(-42% to-49%; P < 0.05; also confirmed at the protein level) and increased expression of the vitamin D receptor gene(209%-321% vs controls; P < 0.05). There was no effect of D-vitamins on the expression of transforming growth factor-β1 and collagen type 1(chain α1). The lowest uptake of proline, a main component of collagen, was observed in calcipotriol-treated PSCs.CONCLUSION The three D-vitamins inhibit, with similar efficiencies, activation of PSCs in vitro, but cannot reverse the phenotype once the cells are fully activated.

Different characteristics of chronic dibutyltin dichloride-induced pancreatitis and cholangitis in mouse and rat

Background:Current animal models of chronic pancreatitis(CP)often provide only limited pathophysio-logical insights since they incompletely reflect the human disease.CP induced by injection of dibutyltin dichloride(DBTC-pancreatitis)shares with human CP the important feature of extended fibrosis and would be an even more attractive model if it could be transferred from rats to mice,as recently sug-gested in the context of combined ethanol and DBTC application.This study aimed to evaluate the effects of DBTC in pancreas and liver of C57BL/6 mice,a strain commonly used to engineer genetic mouse mod-els.Methods:C57BL/6 mice and Lewis rats were exposed to variable doses of DBTC.After an investigation period of up to 4 weeks,laboratory findings and histopathological changes of pancreas and liver were evaluated.Results:Chronic DBTC-pancreatitis in rats was characterized by acinar cell damage,ductal changes,fi-brosis,and inflammatory cell infiltrates.Mice treated with DBTC at 6–8 mg/kg body weight,the standard doses in rats,showed transient increases of lipase activities but no morphological signs of chronic DBTC-pancreatitis 4 weeks after injection of the drug.Increased doses of 10–12 mg/kg DBTC were intolerable due to their high toxicity.In contrast,mice and rats presented with a similar histopathology of the liver that can be characterized as a chronic-proliferative DBTC-cholangitis with predominating damage and proliferation of the small bile ducts as well as secondary portal inflammatory cell infiltrates and a begin-ning portal fibrosis.Conclusions:The DBTC-model cannot be transferred from rats to C57BL/6 mice with respect to chronic DBTC-pancreatitis,but might be of interest to study DBTC-cholangitis in both species.

YAP activates pancreatic stellate cells and enhances pancreatic fibrosis

Background:Pancreatic stellate cells(PSCs)foster the progression of pancreatic adenocarcinoma and chronic pancreatitis(CP)by producing a dense fibrotic stroma.However,the incomplete knowledge of PSCs biology hampers the exploration of antifibrotic therapies.Here,we explored the role of the Hippo pathway in the context of PSCs activation and experimental CP.Methods:CP model was created in rats with the tail vein injection of dibutyltin dichloride(DBTC).The expression of Yes-associated protein(YAP)in CP tissue was assessed.Primary and immortalized rats PSCs were treated with the YAP-inhibitor verteporfin.Furthermore,YAP siRNA was employed.Subsequently,DNA synthesis,cell survival,levels ofα-smooth muscle actin(α-SMA)protein,presence of lipid droplets and PSCs gene expression were evaluated.Upstream regulators of YAP signaling were studied by reporter gene assays.Results:In DBTC-induced CP,pronounced expression of YAP in areas of tubular structures and periduc-tal fibrosis was observed.Verteporfin diminished DNA replication in PSCs in a dose-dependent fash-ion.Knockdown of YAP reduced cell proliferation.Primary cultures of PSCs were characterized by a de-crease of lipid droplets and increased synthesis ofα-SMA protein.Both processes were not affected by verteporfin.At the non-cytotoxic concentration of 100 nmol/L,verteporfin significantly reduced mRNA levels of transforming growth factor-β1(Tgf-β1)and Ccn family member 1(Ccn1).YAP signaling was acti-vated by TGF-β1,but repressed by interferon-γ.Conclusions:Activated YAP enhanced PSCs proliferation.The antifibrotic potential of Hippo pathway in-hibitors warrants further investigation.